If Great British Bake Off judges Mary Berry and Paul Hollywood find the icing of their contestants' cakes a little lumpy this season, they should direct their questions to Tate & Lyle Sugar.

In January, the privately owned company, which was broken off from Tate & Lyle PLC in 2010 and sold to the ASR Group for £211m, changed its legendary icing sugar mix. Instead of using the anti-clumping tricalcium phosphate agent E341, the company is now using cornstarch to do the same thing.

The elite bakers of the British Sugarcraft Guild were not impressed. "Problems with your icing?" the group's Facebook page asks, telling its members of the change: "Please advise the Tate & Lyle customer service department of any problems you have with the new formular [sic]".

According to one member, the company said it would look into whether to change the recipe back. "They say they use independent food experts but I've advised them to use royal icing experts!" she said.

The problem the bakers report is that their icing, especially when whipping up a thick royal icing, has become too gritty. It is "not smooth and fluffy like normal," one BSG member said of how her icing turned out when using the new mix. Others said they switched brands as soon as they found the recipe had been switched.

"I now can't have it at all as I'm allergic to modified corn maize and potato starch," said another. Tate and Lyle did not respond to a question about how the change would impact its customers with allergies to corn.

'In-house' decision to change recipe

The decision to change the recipe "was taken after both in-house and external testing showed that maize starch greatly reduces the possibility of caking when icing sugar has been stored in less than ideal conditions", Tate and Lyle Sugar said. That means the product can keep longer.

The company is still making the original recipe but selling it only to a select few industrial-scale buyers "where their compliance with ingredient labelling requirements would make a mid-contract ingredient change extremely difficult".

Tate and Lyle Sugar did not answer questions about whether it was considering a switch back to the previous recipe. This is not the first time a company has experienced uproar after altering a well loved and established product.

Most recently, in January, Cadbury changed the chocolate recipe used in the coating of its famous Creme Egg. The switch from Dairy Milk chocolate in the recipe to "standard cocoa mix chocolate" outraged fans.

In the past, declining customer demand for a product has prompted companies to back pedal. The most famous example is New Coke. In 1985, Coca-Cola believed it could improve the formula for the nearly 100-year-old fizzy drink. The backlash included boycotts and public protests, and the company returned with a product called Coca-Cola Classic.

Other examples were born from legitimate health concerns. When Frito-Lay in 1998 replaced the fat in its snacks, including crisps such as Doritos, with a fat-replacement compound called Olestra, it gave some people "anal leakage" and other problems digesting it. The line of "fat-free" products was discontinued.

Concern around the icing sugar switch, though, has only arisen among bakers. Tate and Lyle did not address questions put to the company about whether sales of their icing sugar had been affected by the switch.